a) Field of the Invention
The present invention relates to a manufacture of a semiconductor device, and more particularly to a technology of manufacturing a semiconductor device with a p-n junction or junctions formed by using group III-V compound semiconductor.
b) Description of the Related Art
A conventional compound semiconductor device has been formed mainly on a flat substrate, particularly a substrate having a flat surface of crystallographic (1 0 0) plane, and made of GaAs, InP or other compound semiconductors, because a semiconductor crystal of excellent quality can be epitaxially grown relatively easily on the substrate having the (1 0 0) plane and also because a flat wafer can be easily cleaved to fine or minute semiconductor devices.
The manufacture of semiconductor devices having a new structure has been studied recently by epitaxially growing a semiconductor crystal on a semiconductor substrate having not only a flat (1 0 0) plane surface but also other surfaces of other crystal orientations as well as steps, grooves, or ridges. It is expected that semiconductor devices having an excellent performance difficult to be realized on a (1 0 0) plane substrate can be manufactured by using substrates having surfaces of crystal orientations other than the (1 0 0) plane as well as steps, grooves, or ridges.
It is an important technique of semiconductor device manufacture to control the conductivity type and carrier concentration of a semiconductor crystal by doping impurities. It is therefore important to have a knowledge of crystal orientation dependence of p-type or n-type impurity doping in a crystal epitaxially grown on a semiconductor substrate.
The inventors have studied the crystal orientation dependence of the doping characteristics of dopants in group III-V compound semiconductors grown by metal organic vapor phase epitaxy (MOVPE), by using dopants such as group II acceptors (Zn and Mg), group VI donors (Se), and group IV donors (Si). For details, reference may be made to Kondo, et al., "Crystal orientation dependence of impurity dopant incorporation in MOVPE-grown III-V materials", J. Crystal Growth, vol. 124, p.449, (1992), which is incorporated herein by reference.